1. Field of the Invention
The present invention relates to a silent chain and a silent chain transmission device made up of the silent chain and a sprocket.
2. Description of the Related Art
Conventionally, a silent chain is known in which a guide row made up of a pair of left and right guide plates and a middle plate disposed between the pair of left and right guide plates and a non-guide row made up of a plurality of inner plates are alternately connected in a chain longitudinal direction by a pair of locker pins made up of a long pin and a short pin to be inserted into a pair of front and rear pin holes provided on the middle plate and the inner plates (for example, refer to Japanese Patent Application Laid-open No. 2002-130384).
In addition, a silent chain transmission device is known which is capable of transmitting power among a plurality of sprockets by winding a silent chain around the plurality of sprockets.
Generally, in a silent chain transmission device made up of a silent chain and a sprocket, a sprocket pitch is defined as an interval between intersections of a standard pitch line of the sprocket and an imaginary line that passes through respective tooth bottoms.
In addition, a tooth shape of the sprocket and shapes of the respective plates of the silent chain are designed so that the silent chain can be wound around the sprocket in an optimal manner in a state where a pitch between rolling points that is an interval between rolling points of a pair of locker pins inserted into respective pin holes of the silent chain is consistent with the sprocket pitch.
Presupposing the occurrence of elastic elongation and wear elongation, a known silent chain such as that described in Japanese Patent Application Laid-open No. 2002-130384 is designed such that a pitch between rolling points in at least a non-guide row is smaller than a sprocket pitch in a low load state where the silent chain is subjected to such a load that elastic elongation hardly occurs as shown in the table in FIG. 7.
This design takes into consideration that, when elastic elongation and wear elongation occur during actual use, a difference between the sprocket pitch and the pitch between rolling points decreases and winding of the silent chain around the sprocket improves.